Semiosis is the process of connecting a meaning to a sign, which is anything that stands for or indicates something. When the traffic light turns green, a driver knows it's time to go.
In semiosis, a sign may be an image, an action or event, a sound, or a word. A thumbs-up emoji in response to a text message indicates agreement. An EXIT sign in a theater shows you the way out. If you hear applause, you know that people are appreciating something, but if you hear a siren, you know to watch out because of an emergency. The process of semiosis involves the sign itself, the meaning it carries, and an interpreter who is able to connect the sign to its meaning.